Angle grinders (angle grinders) are quite popular tools that are often used in the household. Like any other devices, they periodically fail during operation. Most often this happens due to the fact that the lubricant of the gearbox for angle grinders has dried out. Therefore, people who are going to use such power tools should become familiar with the features of their lubrication.
The angle grinder gearbox is the most important part on which the operation of the power tool depends
The role of lubricant and its characteristics
A distinctive feature of the grinder is the gearbox, which consists of gears with a helical structure. During operation of the tool, this unit takes on a significant load and is subject to wear more than others. The rotor of an angle grinder creates a torque passing from a small gear with oblique teeth to its large counterpart. The last gear has a shaft on which the working tool (mill, emery wheel, brush) is attached.
As the gear teeth move and rub against each other, the temperature rises. And this leads to weakening of the metal and rapid wear. To prevent negative consequences, special compounds are introduced into the rubbing units, which significantly reduce deformation and prevent the parts from heating up intensely.
Lubricant for power tool gearboxes must have the following parameters:
- Its viscosity must be no more than 800 units.
- The tensile strength exceeds 120 pascals.
- The composition must be classified as refractory (over +100°C).
Refractory branded lubricant Source besplatka.ua
In this case, the mixture should:
- have water-repellent properties;
- hold firmly on parts;
- do not cause corrosive processes;
- do not contain mechanical additives.
But besides the gearbox, the grinder has two types of bearings, which also need lubrication. One of them helps the electric motor. The other serves as a support for the spindle of the large gear in the gearbox. These bearings operate under different conditions and require different oil compositions.
Application order
The grinder maintenance process consists of several steps. First, you will need to open the gearbox, then remove the old lubricant, apply new one and check the correct application.
Removing old lubricant is a mandatory step, because when mixed with fresh lubricant, it will not allow it to work correctly, and the whole procedure will not bring the desired result.
To disassemble the angle grinder gearbox, you will need to unscrew the 4 screws on its cover.
After removing the cover, you will see two bevel helical gears - a large and a small one. The small one is anchored and powers the larger one. The latter, in turn, is mounted on a secondary shaft, to which a cutting or grinding disc is attached.
The disassembled gearbox must be thoroughly cleaned of old lubricant. It no longer performs its functions and has accumulated solid wear particles from moving parts.
Used grease is removed with a rag or paper towel. You can also remove the parts and wash them in gasoline or solvent, and then dry them thoroughly.
When cleaning and flushing the gear housing, be careful with the rear spindle bearing. If it is needle-like, do not wash or lubricate it. Needles may fall out of a worn cage or outer race. This can cause a lot of problems, including the need to replace the bearing.
When washing the gearbox housing, hold the angle grinder with the engine facing up so that the dirty solution does not flow down the rotor shaft into the bearings and electrical elements.
Before applying new lubricant, it must be mixed - there should be no lumps or foreign impurities in it. The lubricant is distributed on the gears in a thin layer so that it completely covers the teeth.
It is more convenient to introduce lubricant into the bearings using a syringe. The composition is also stuffed into the gearbox housing - this is necessary for “safety net”. If the lubricant comes off the gears or there is too little of it, the parts will not run dry.
The last step when servicing your angle grinder is to ensure that the lubricant is properly applied and distributed inside the gearbox. When the gear unit is assembled, turn on the power tool without load for several minutes, while making sure that there are no extraneous sounds, smells, etc. When they occur, the angle grinder is immediately disconnected from the network.
In addition, the heating of the gearbox is checked. The lubricant must distribute heat evenly, so the temperature of the gear unit should not be too high.
After operating the angle grinder for a short time, remove the gearbox cover again and inspect the gears for the presence of lubricant. If it is not there, it means that too little was put in and you should add more; if the lubricant is squeezed out of the cracks, you need to remove the excess.
Recommendations from foreign manufacturers
Commercial policy is a tricky thing. Therefore, all foreign manufacturers developing power tools produce “special” lubricants only for their products. Naturally, such compositions differ significantly in price compared to conventional mixtures. But, in practice, they do not stand out from the latter in anything serious.
Meanwhile, manufacturers of imported angle grinders recommend using only their specialized lubricant. This is justified by the fact that the uniquely developed composition significantly extends the service life of the mechanisms and therefore the warranty service is extended for a longer period.
Branded Bosch lubricant Source stroyinstrument.by
And if the conditions are not met, they refuse free service in case of breakdowns. Reasoning that they arose due to the use of low-quality and cheap lubricant. And in order to justify the high cost of their consumables, they add expensive and rare components to the composition.
Explanation of the markings that the branded lubricant for angle grinders has:
- If molybdenum is introduced as an additive, then the marking is MOS2.
- When the viscosity grade is increased to the second, NLGI2 is indicated.
- To confirm the ISO standard, set ISOL-XBCHB 2.
- German quality is indicated by the DIN marking.
- For a special standard from Germany for type “K” the numbers 51825 are prescribed.
Literally all famous brands use such techniques. From Makita and Bosch to Hitachi and Interskol.
See also: Catalog of companies that specialize in paints and varnishes and related work
Domestic lubricants
Russian power tool manufacturers are trying to keep up with foreign industry leaders. But in terms of creating lubricants, they are already worthy competition. Domestic products based on machine oils are not much different in quality from imported analogues. But the price is much cheaper.
Domestic lubricant for drills and gearboxes Source levsha24.ru
Therefore, it makes sense for our consumers to use Russian products, which are perfect for both domestic instruments and all Western ones. For example, the grinder gearbox lubrication from Nanotech has proven itself to be excellent. The MetalPlak Electra series has become popular due to its low cost and excellent quality.
For bearings
When manufacturing an angle grinder, bearings already filled with a lubricant are installed in it. But intense heating during operation transforms the mixture into a liquid state, and it flows out. Therefore, during scheduled maintenance, the bearings must be filled each time.
It is necessary to select the composition so that it meets the requirements:
- increased sliding;
- reduced friction;
- performed cooling;
- prevented corrosion;
- protected from dust;
In addition, it is necessary that the properties of the lubricant remain unchanged at temperatures up to +150°C. And lithium compounds have proven themselves better than others for parts in gearboxes. Mixtures CIATIM-203 and VNIINP-242 are also good.
Heat-resistant grease for bearings Source stpulscen.ru
But the bearing, which is installed to help the electric motor, has a different temperature regime. The rotation speed and load also differ. Therefore, when choosing a lubricant, not only general protective factors are taken into account, but also these indicators. And here you will need pigment lubricants VNIINP-246 and VNIINP-235.
Methods
In modern mechanisms, the following methods of cooling the gearbox are used.
- Water cooling is a constructive design solution (artificial water cooling). Used in special gear mechanisms in 1 of 2 options.
- In the first case, perforation of the body is provided (the installation of several channels through which water is supplied).
- In the second, water cooling is carried out using a coil (installed in the crankcase block filled with lubricant).
- Air cooling of the gearbox. May be artificial or natural.
- With artificial air cooling, a fan impeller (centrifugal) is installed on the worm. Fastening is carried out through the casing in which the impeller is placed. In this case, the body ribs should run along the axis of the box. Artificial air cooling is important to ensure the operation of powerful dimensional gearboxes.
- The self-venting air cooling system is based on the use of aluminum boxes with vertical ribs. This approach is good for lightweight, small-sized devices.
Correct lubricant change process
The performance of an angle grinder directly depends on the technical literacy of its owner. In order for a power tool to last as long as possible and not malfunction during operation, it is necessary to follow certain rules. And they concern not only the conditions, but also the application of knowledge. And directly – when, where and how much lubricant needs to be distributed.
Replacement periods
Grease grinder lubrication changes completely in three cases:
- According to the drawn up schedule of preventive work.
- When replacement of failed gearbox parts is required.
- When installing new bearings on the rotor.
You can also determine the need for replacement visually. When the lubricant turns black from dust and tiny metal shavings, it means the time has come.
How to lubricate the gearbox of an angle grinder
There are several options for the coolant used. Angle grinders use a fairly wide range of substances. Which one is considered suitable under certain conditions is up to the user to decide. How to lubricate the gearbox?
- special lubricants for a specific brand or model of grinder;
- ordinary grease or lithol;
- compositions suitable for any electric tool;
- self-made mixture.
Each manufacturer produces certain consumables for its equipment, including lubricant. It is optimal in that it is suitable for specific materials of the gearbox and housing. It is also created taking into account the operating conditions of the device. The cost may seem significant, but it is less than the cost of a new angle grinder.
Litol (solid oil), available in every garage, is not considered the right solution. They are not designed to withstand the temperatures that gears reach. Therefore, lubrication does not work, and instead of creating a positive effect, it creates difficulties. During operation, it will leak from the housing, and the rubbing parts will fail faster.
Multi-purpose lubricants may also not take into account certain speeds and temperatures of gearbox operation. This option is also bad because such a lubricant may not work on the specific steel used. A certain effect will appear, but no better than from special lubricants for grinders.
Manually created lubricant will help out in case of urgent need for lubrication. It is recommended to use automotive lubricant for CV joints as a basis - it is resistant to loads, humidity, and temperature fluctuations. In order to obtain the required density, oil is added - for example, MS-20. The mixture is stirred until complete mutual dissolution. Alternative: “Ciatim” + TAD-17. Various experts and thematic forums can offer a lot of compositions, which should be used with caution. Buying a new power tool, especially a professional-grade one, will be a significant investment of time and money. It will be cheaper to buy the appropriate composition.
Briefly about the main thing
Lubrication is an important element in properly ensuring the performance of a moving power tool. But each of their types has its own requirements. The grinder requires refractory lubricants with a viscosity of up to 800 pascals per second. Capable of exceeding tensile strength of 120 units.
Although Western manufacturers of power tools require that only branded lubricants be used for their products, the recommendations can often be ignored. Because domestic factories supply the market with cheaper products that are not inferior to imported analogues.
When completely replacing the lubricant in an angle grinder, it is necessary to ensure that the old composition is completely removed from the surface of the parts. The fresh mixture is applied without excess, in a uniform thin layer. Upon completion of the operation, the operation of the tool at idle speed is checked.
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Homemade mixtures
People who do not know how to lubricate the angle grinder gearbox can use homemade mixtures. Quite often people mix several compounds together.
For example, to ensure the required level of adhesion, you can use lubricant for CV joints. Before adding it to the gearbox, it is mixed with MS-20 oil to obtain the desired consistency.
The gearbox is an important part that is responsible for the performance of the angle grinder. It needs to be lubricated regularly for the sander to work well. However, before you do this, you need to figure out how much oil to add and how to use it correctly.
